Structural finite element analysis of stiffened and honeycomb panels of the RASAT satellite

This paper describes the structural analysis carried out on the main stiffened and honeycomb panels of the RASAT satellite. The analysis here supports the design process and aims to ensure that the panels survive structural qualification testing. This analysis therefore forms part of the overall qualification process. The stiffened and honeycomb panels being considered in this document form the outer box structure of the satellite. These panels consist of the space-facing facet (SFF), solar panels including solar cells and earth facing facet (EFF). All these panels are key parts of the satellite's structure and are critical to mission safety. The separation panel is particularly highly loaded, since it supports the battery pack, reaction wheels, gyro module, magnetorquer rods and sun sensors. The separation panel also supports the solar panel assembly. The solar panels are also of critical importance, their integrity maintaining the required power supply to operate the satellite's electronic systems. As being different from the SFF and EFF, the solar panels are made of aluminum honeycomb panels. The solar panels are particularly sensitive, as they carry arrays of delicate ceramic solar cells together with their wiring. Throughout all loading conditions experienced during the mission, the solar panels must continue to support the solar cells without cell failures or wiring disconnections. The EFF is perhaps the least critical of the stiffened panels but still must support the top of the solar panel assembly and must carry various antennae. The main objective of this study is to assess the strength and vibration response properties of the stiffened and honeycomb panels by conducting static stress and modal analyses. For the case of static loading, the reliability can be estimated with great efficiency, whereas for dynamic loading the performance depends on the considered frequency range. The obtained results are very significant in that, they illustrate the feasibility of a full scale analysis for structural reliability in a design context for large-scale structures. The analyses are conducted by means of the finite element method. For the static case, the SFF and EFF are meshed with hex elements and the honeycomb panels are meshed with solid brick and shell elements. For the calculated gRMS value the static analysis had been conducted in each axis of the panel assembly. For the dynamic case, the same finite element mesh and material properties had been used. In this case, the boundary conditions are applied in such a way to determine the mode shapes and the resonance frequencies. Furthermore, the stress values had been determined with respect to the applied static and dynamic loading cases. They had been compared With the allowable stress values of the materials. In this paper the complete finite element analyses procedures are described and the results of the analyses are presented. According to the computed results, some conclusions are drawn in order to guide experimental qualification tests